I think you will be ok installing the 1111KIT under the Honda rack rails, since as was pointed out earlier, they do mount Under the Honda rails and sit on the frame.
You mentioned possibly raising the rails or brackets, but that probably won't work because the seats would no longer fit if you raised the rails any more than the thickness of the Givi hardware.
You mentioned possibly raising the rails or brackets, but that probably won't work because the seats would no longer fit if you raised the rails any more than the thickness of the Givi hardware.